The Wavetek Model 404 Signal Generator (military designation of UGM- 11) was a commercial data transmission test set which could also simulate a crypto signal for various types of crypto devices. A selection of different baud rates was available and distortion could also be introduced into the signal.
Right Side View
Left Side View - Note the Mode switch at the left.
Full Front View
Photos courtesy of: firstname.lastname@example.org ; Virginia Beach, VA